The present invention relates to electrical measurements and, in particular, to the testing of semiconductor devices.
To fully test many devices it is necessary to not only test the direct current (DC) characteristics of the device, but also to test the high frequency (HF) characteristics. The HF frequency characteristics may include radio frequency (RF) characteristics, pulse characteristics or both. Measuring pulse characteristics have similar issues to measuring RF characteristics because fast rise time and fall time pulses (as well as fast pulse repetition rates) have substantial high frequency content.
As the number of devices on a board, chip or wafer increase, it has become more important to be able to quickly, as well as accurately, make measurements. In addition, when many devices are being tested at the same time, cabling to the device under test (DUT) also becomes an issue. It may be difficult to bring all of the desired cable connections close to the DUT, this is particularly true when both HF and DC measurements are desired. It is particularly desirable to avoid re-cabling for each type test because of the time involved and to avoid doubt of correlation of measurement results between HF and DC regimes. For speed and reliability, using the same test pins for both HF and pulse testing is desired, but switching the connections at the DUT greatly increases the complexity of the test head setup.